“They are not always going to be giving away free bags,” Sifuentes said. “I think it’s going to take a change in habit, but I’ve got to start remembering to bring them.”

Across the city, workers in supermarkets, drugstores, beauty-supply shops and other retail outlets were posing an entirely new question at the checkout counter: The ubiquitous refrain of “Paper or plastic?” replaced by “Did you bring your reusable bag?”

The new law, which the Seattle City Council approved in December, requires retailers to charge 5 cents for each paper bag they give out. Some stores on Sunday were also charging 10 cents for heavier plastic bags — a choice the city left to their discretion.

Stores may offer small paper bags for free.

Small plastic bags used for meat, fruit and bulk items, as well as those used for dry cleaning and newspapers, are also exempt. Customers with electronic benefit transfer (EBT) cards, used for food stamps, are exempt from the fees.

Retailers could be fined $250 for failing to comply.

Across Seattle, most people interviewed Sunday were either unaware the ban was now in effect, were confused about which retailers were required to comply, or simply forgot to grab their reusable bags from their house or cars.

At Safeway’s Pinehurst store, a customer named Alex said he’s upset enough that he’ll likely drive to Shoreline for his shopping, just to avoid it. Bags for the $300 worth of groceries he buys each time he shops will certainly add up, he said.

“It’s an additional expense,” he grumbled.

But Midori Tanaka said she sees no point in driving out of her way just to avoid a 5-cent fee. She had forgotten to bring her reusable bags and paid for paper, but said she has to remember to bring them in the future. “I’ll just have to make it a new habit,” she said.

Some people remembered voting against the ban three years ago and were surprised to find that it was back.

The Seattle City Council approved the plastic-shopping-bag ban in December 2011, three years after voters rejected the city’s previous attempt to ban the bags. According to Seattle Public Utilities, Seattleites use 292 million plastic bags a year but recycle only 13 percent of them, resulting in clogged landfills and harm to Puget Sound wildlife.

Seattle is following the lead of a number of cities across the state, the country and the world — including Mexico City and Los Angeles — that have banned plastic bags.

Edmonds banned them since 2010, although shoppers there can still get paper bags for free.

City Councilman Strom Peterson, who was a major proponent of that ordinance, said businesses and customers have adjusted. “I would get an occasional email — one a quarter — from people upset about their ability to pick up after their dog,” Peterson said. “Nine in 10 of the complaints were about that,” he said.

Antonio Lopez was shopping at the Grocery Outlet in the Central District and got a free paper bag because he uses an EBT card. He still doesn’t like the new ordinance. “This is a new tax at a time the economy is so bad,” he said. “It’s just taking money away from people.”

Greg McNair, who was walking two blocks to his home with the milk and other breakfast items he had bought for his family, said he’s not sure what to think about it.

He paid a total of 25 cents for two heavy plastic bags and a paper bag. If the new ban helps the environment, he said, then it’s a good thing.

But, “Thank God I had enough to pay it,” McNair said. “Sometimes you go to the grocery store with just enough money to buy what you need.”

Octaiviea Townsend had her arms full of reusable bags as she headed into the QFC store on Rainier Avenue South.

“I’m actually only going in for produce, so I have way more than I’ll need,” she said. “It’s just backup.”

Townsend said she thinks the ban is a good idea. “Really, it’s bigger than these grocery stores,” she said. “It’s about community and doing the right thing.”